In the end, a lot of people are willing to write open source just for the sake of having it as it scratches their own need and isn't otherwise monetizable or they just think it should exist. I would never even consider touching a GPLv3 licensed UI library component, for example.
It's not always the most appropriate license and if a developer wants to use a permissive license, they are allowed to. This isn't an authoritarian, communist dictatorship, at least it isn't where I live and to my dying breath won't be.